1. Field of Invention
The present invention relates to a three-dimensional Micro-electro-mechanical-system sensor, in particular to such a MEMS sensor which integrates in-plane electrodes with out-of-plane electrodes along a vertical direction.
2. Description of Related Art
MEMS devices are used in a wide variety of products, of which one application is capacitance-type sensors, such as accelerometer, microphone, etc. There are two types of such sensors, i.e., in-plane sensors and out-of-plane sensors. The former ones are used to sense a capacitance variation in a horizontal direction (x-y plane), and the latter ones are used to sense the capacitance variation in a vertical direction (z axis). With respect to in-plane sensors and methods for making such sensors, prior art U.S. Pat. Nos. 5,326,726; 5,847,280; 5,880,369; 6,877,374; 6,892,576; and U.S. publication No. 2007/0180912 disclose several examples. With respect to out-of-plane sensors and methods for making such sensors, prior art U.S. Pat. Nos. 6,402,968; 6,792,804; 6,845,670; 7,138,694; and 7,258,011 disclose several examples. However, these prior art references do not disclose a sensor capable of detecting the capacitance variations in three dimensions.
In view of above, the present invention overcomes the foregoing drawback by providing a three-dimensional Micro-electro-mechanical-system sensor which integrates in-plane electrodes with out-of-plane electrodes along a vertical direction. Thus, the sensing function of the sensor is improved, and the area of the MEMS device is reduced.